Assessments: Assessments will include subjective quality of life; symptoms that are "syndrome defining" for Gulf War illness (like fatigue and muscle problems); and other symptoms and conditions reported to occur more commonly in GWV (like sleep problems). Analyses will show whether Q10 led to improvements when compared to placebo; whether higher Q10 doses improved outcomes more than lower doses; and whether people with certain symptoms or characteristics get more benefit than people with other symptoms or characteristics.